Vascular filter

ABSTRACT

An inferior vena cava filter ( 340 ) for use in the inferior vena cava ( 4 ) to capture thrombus ( 8 ) passing through the inferior vena cava ( 4 ) towards the heart and lungs to prevent pulmonary embolism comprises a proximal support hoop ( 302 ), a distal support hoop ( 312 ) and a plurality of support struts ( 303 ) extending between the proximal support hoop ( 302 ) and the distal support hoop ( 312 ). The filter ( 340 ) also comprises a plurality of capture arms ( 121 ) which are movable from a capturing configuration to an open configuration. The capture arms ( 121 ) are biased towards the open configuration. A biodegradable suture holds the capture arms ( 121 ) in the capturing configuration.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/822,680, filed on Jul. 9, 2007, now U.S. Pat. No. 8,162,970 whichclaims benefit of U.S. Provisional Application No. 60/831,674, filed onJul. 19, 2006, both of the contents of which are incorporated herein byreference.

INTRODUCTION

This invention relates to a vascular filter. In one particularembodiment this invention relates to an inferior vena cava filter.

It is known to implant a vena cava filter in the vena cava to preventthrombus entering the right atrium. They have been in use clinically fora number of years. The use of filters implanted in the inferior venacava is for the prevention of pulmonary embolism in high-risk patients.

Deep vein thrombosis (DVT) and pulmonary embolism (PE) are commonmedical conditions that contribute substantially to individual patientmorbidity and mortality as well as global healthcare costs. DVT developswithin the deep veins of the lower extremities but also can involve orarise solely from the veins of the pelvis or the upper extremities. Whenblood clots float from a large vein in the lower body through the venacava to the heart and lungs they may cause pulmonary embolism (PE).Because DVT and PE share a common pathophysiology and frequently occurtogether they are currently being perceived as two points on thecontinuum of a single disease process identified as venousthromboembolism (VTE).

Experts estimate that pulmonary embolism (PE) affects over 1.2 millionpeople in the US and Europe every year. The highest recognized incidenceof PE occurs in hospitalized patients, with 60% of hospitalized patientshaving had a PE. However, the diagnosis of PE is missed is missed inapproximately 70% of those patients. PE is the third leading acutecardiovascular cause of death in the developed world accounting forapproximately 10% of in-hospital deaths. In spite of the potentiallydisastrous outcomes, not all surgical patients receive appropriateprotection. This is in part due to the fact that current treatments arenot ideal. There are two broad categories of vena cava filters:permanent and retrievable. Permanently implanted devices can migrate andtheir clinical use is not preferred in younger patients. Retrievablefilters can be notoriously difficult to remove and the additionalintervention poses risks to patients.

Common clinical risk factors for DVT and PE include age older than 50years, prolonged immobilization because of illness, travel or surgery,oestrogen therapy, pregnancy and malignancy among others. A geneticpredisposition has also been suggested.

Candidates for inferior vena cava (IVC) filter placement are typicallyevaluated for the presence of lower-extremity DVT and/or PE. Imagingmethods used to document the presence of lower-extremity DVT includeultra sound and peripheral venography. PE can also be diagnosed by usingnuclear medicine ventilation-perfusion scans. Although pulmonaryarteriography remains today's criterion standard for confirmation ofdiagnosis, an increasing number of centres are using helical computedtomography (CT) to evaluate patients in whom PE is suspected. Magneticresonance angiography (MRA) of the pulmonary vasculature is alsoperformed as an alternative diagnostic imaging technique.

Inferior vena cavography is currently the modality used most commonly toassess the inferior vena cava (IVC). Access to the IVC is typicallyachieved via a left or right femoral vein or via the right internaljugular vein. Ultrasound may be used to guide the puncture.

Although the indications for IVC filter placement have expanded over theyears, a DVT or PE in a patient with a contraindication foranticoagulation therapy remains the most frequent indication, accountingfor 65% of patients undergoing IVC filter placement. Insertion of a venacava filter is indicated for patients who:

-   -   Cannot receive medications that can dissolve the clot    -   Have a thrombus in a deeply situated vein    -   Experience complication of anticoagulation therapy such as        bleeding    -   Experience failure of anticoagulation therapy to prevent        pulmonary embolism    -   Have an embolus in the lungs removed (pulmonary embolectomy)    -   Have a recurrent embolism while receiving adequate medications    -   Have significant bleeding complications during anticoagulation

The inferior vena cava (IVC) is the largest venous structure in thebody. It drains the venous return from the lower extremities, pelvis,and abdomen into the right atrium. Before filter placement, an inferiorvena cavogram is obtained to assess caval diameter and patency, theextent of thrombus and to understand the presence of any venousanomalies.

Filters can be placed by either a femoral or jugular approach. The basicprinciple for femoral insertion is to choose the side that has patentand preferably thrombus-free veins. Right femoral puncture is preferablebecause there is less angulation in the iliac veins. A careful leftfemoral approach may be successful if a right-sided puncture iscontraindicated. A jugular approach can be used when there is inferiorvena cava or bilateral iliofemoral thrombosis. For the femoral approach,the common femoral vein is punctured, while for the jugular approach,the puncture site is at the internal jugular vein. Another inferior venacavogram is performed after filter placement to check the position andstability of the filter.

This invention is aimed towards providing an improved vascular filter.

STATEMENTS OF INVENTION

According to the invention there is provided a vascular filtercomprising:—

-   -   one or more capture members for capturing thrombus passing        through a blood vessel; and    -   one or more support members for supporting the one or more        capture members relative to a wall of the blood vessel.

By capturing the thrombus, the filter prevents the thrombus from passingto the heart or lungs, which may cause pulmonaryembolism.

By supporting the capture members this ensures that the capture membersare maintained in the desired location in the blood vessel.

In one embodiment of the invention the support member is configured toextend circumferentially around a wall of a blood vessel. The supportmember may extend circumferentially in a wave pattern. The supportmember may extend circumferentially in a zigzag pattern. The supportmember may extend circumferentially in a crown pattern. The supportmember may extend circumferentially in a sinusoid pattern. Thewave/sinusoid pattern of the support member facilitates collapse of thesupport member for ease of delivery and/or retrieval through the bloodvessel. The support member may be configured to extend longitudinallyalong a wall of a blood vessel. A distal end of the support member maybe located distally of a distal end of the capture member. A proximalend of the support member may be located proximally of a proximal end ofthe capture member. The filter may comprise a first support memberconfigured to extend circumferentially around a wall of a blood vessel,a second support member configured to extend circumferentially aroundthe wall of the blood vessel, and a third support member configured toextend longitudinally along the wall of the blood vessel. The thirdsupport member may connect the first support member to the secondsupport member. The first support member, the second support member andthe third support member may be formed integrally. The first supportmember may be provided at the proximal end of the filter. The secondsupport member may be provided at the distal end of the filter.

In one case the support member comprises a body portion and one or moreopenings in the body portion. The openings in the support memberfacilitate tissue ingrowth. A drug coating may be added to the structureto manage the tissue response at and near the site of implant. This maytake the form of a polymer or metal coating containing thepharmaceutical that releases the drug in a controlled manner or aseparate or integral sleeve that covers the entire device and isimplanted between the device and the vena cava. This sleeve may bebio-degradable or bio-resorbable. The support member may comprise amesh. The support member may comprise a trellis.

In another embodiment the support member comprises an anchor member. Theanchor member may be configured to be embedded at least partially into awall of a blood vessel. The anchor member may comprise a barb element.The anchor member may be configured to be removed from a wall of a bloodvessel. The anchor member may be configured to be removed from a wall ofa blood vessel upon application of a removal force in a directionsubstantially parallel to the longitudinal axis of the blood vessel. Atleast part of the anchor member may be biodegradable and/orbioabsorbable.

In another case at least part of the support member is biodegradableand/or bioabsorbable.

In one embodiment the support member is movable between a deliveryconfiguration and a deployed configuration. The support member may becollapsed in the delivery configuration. The support member may beexpanded in the deployed configuration. The support member may be biasedtowards the deployed configuration.

In one case at least part of the capture member is biodegradable and/orbioabsorbable. All of the capture member may be biodegradable and/orbioabsorbable.

In another case the capture member comprises one or more predeterminedfailure points. This enables controlled biodegrading/bioabsorbing of thecapture member. The capture member may have a designed in reducedtensile strength failure point. The capture member may comprise one ormore openings through a wall of the capture member at the failure point.

In one embodiment the filter comprises one or more linking members tolink one capture member to an adjacent capture member. At least part ofthe linking member may be biodegradable and/or bioabsorbable.

In another embodiment the capture member is attached to the supportmember. The capture member may be attached to the support member in asnap-fit arrangement. Part of the capture member may be wrapped aroundthe support member. The capture member may be provided integral with thesupport member.

In one case the capture member is movable between a capturingconfiguration and an open configuration. The capture members may remainin the capturing configuration while there exists a risk of thrombus.When the risk of thrombus passes, the capture members may then move tothe open configuration. Thus it may not be necessary to retrieve thefilter from the blood vessel. The capture member may be biased towardsthe open configuration. The filter may comprise a holder member to holdthe capture member in the capturing configuration. At least part of theholder member may be biodegradable and/or bioabsorbable. The holdermember may comprise a coil around at least part of the capture member.The holder member may comprise a tube around at least part of thecapture member. The holder member may be permanent, removable orbioabsorbable. The holder member may extend through an opening in thecapture member. The holder member may comprise a suture. The holdermember may comprise one or more predetermined failure points. Thisenables controlled biodegrading/bioabsorbing of the holder member. Theholder member may have a reduced tensile strength at the failure point.The holder member may comprise one or more openings through a wall ofthe holder member at the failure point.

In another embodiment the capture member extends towards an apex. In thecapturing configuration, the capture member may extend towards the apex.The apex may be substantially in-line with a longitudinal axis extendingthrough the centre of a blood vessel. The apex may be substantiallyoffset from a longitudinal axis extending through the centre of a bloodvessel. The offset apex may result in the captured thrombus being offsetfrom the centre of the blood vessel. Thus blood flow through the bloodvessel may be enhanced. Two or more of the capture members may engageone another at the apex. An end of a first capture member may beconfigured to nest with an end of a second capture member at the apex.The capture member may extend in the direction of blood flow through ablood vessel. The capture member may extend in a direction opposite tothe direction of blood flow through a blood vessel. The capture membermay extend in a spiral towards the apex. At least part of the capturemember may extend in a curve. The convex portion of the curve may faceradially outwardly. The concave portion of the curve may face radiallyoutwardly.

In another embodiment the capture member defines a capture region withinwhich thrombus may be captured. In the capturing configuration, thecapture member may define the capture region. The capture region may beconfigured to be located in the region of the centre of a blood vessel.The capture region may be configured to be located in the region of awall of a blood vessel. By locating the capture region in the region ofthe blood vessel wall, this may enhance blood flow through the bloodvessel. The capture region may be substantially annular shaped. Thecapture region may be substantially conically shaped. The capture regionmay be substantially cylindrically shaped.

In one case the capture member is movable between a deliveryconfiguration and a deployed configuration. The capture member may becollapsed in the delivery configuration. The capture member may beexpanded in the deployed configuration. The capture member may be biasedtowards the deployed configuration.

In another case the filter comprises one or more tensioning members totension the capture member. The tensioning member may be movable betweena capturing configuration and an open configuration. The tensioningmember may be biased towards the open configuration. The filter maycomprise one or more connecting members to connect the tensioning memberto the capture member. At least part of the connecting member may bebiodegradable and/or bioabsorbable.

In another embodiment the filter comprises one or more balance membersextending in the opposite direction to the capture member. In a filterconfiguration the one or more balance members may extend in the samedirection as the capture member. The balance member may be attached tothe support member. At least part of the balance member may extend in acurve. The convex portion of the curve may face radially outwardly.

In one case the filter comprises a vena cava filter. The filter maycomprise an inferior vena cava filter.

In another aspect the invention provides a vascular filter assemblycomprising:—

-   -   a vascular filter of the invention; and    -   a delivery device for delivering the filter to a desired        location in a blood vessel.

In one embodiment of the invention at least part of the delivery deviceis movable between a delivery configuration and a deployedconfiguration. At least part of the delivery device may be collapsed inthe delivery configuration. At least part of the delivery device may beexpanded in the deployed configuration. The delivery device may beinflatable. The delivery device may comprise a balloon member.

In one case the delivery device comprises a cover member to at leastpartially cover the filter in the delivery configuration. The covermember may be movable relative to the filter to uncover the filter inthe deployed configuration. The cover member may comprise a sheath.

In a further aspect of the invention there is provided a vascular filterassembly comprising:—

-   -   a vascular filter of the invention; and    -   a retrieval device for retrieving the filter from a location in        a blood vessel.

In one embodiment of the invention the retrieval device comprises anengagement member for engaging the filter. The retrieval device maydefine a reception space for at least partially receiving the filter.The engagement member may be movable relative to the reception space toat least partially receive the filter in the reception space.

According to another aspect of the invention there is provided a methodof treating a blood vessel, the method comprising the step of deployinga vascular filter at a desired location in the blood vessel, the filtercapturing thrombus passing through the blood vessel.

In one embodiment of the invention the method comprises the step ofdelivering the filter in a delivery configuration to the desiredlocation in the blood vessel. At least part of the filter may move fromthe delivery configuration to a deployed configuration at the desiredlocation in the blood vessel.

Deployment of the filter may embed at least part of the filter into awall of the blood vessel.

In one case at least part of the filter moves from a capturingconfiguration in which thrombus passing through the blood vessel iscaptured, to an open configuration.

The method may comprise the step of retrieving the filter from the bloodvessel. The method may comprise the step of removing the filter from thewall of the blood vessel. A removal force may be applied in a directionsubstantially parallel to the longitudinal axis of the blood vessel toremove the filter from the wall of the blood vessel.

In one case the invention provides a method of treating the vena cava.In another case the invention provides a method of treating the inferiorvena cava.

IVC filter placement may be used as a prophylactic means for preventingPE in patients at high risk for thromboembolic events. The invention insuit greatly aids the use of filters during a period of high risk forthromboemembolic events.

The filter of the invention can be used either permanently, ortemporarily with subsequent retrieval or conversion for PE prevention.If the filter is left in place, it functions as a permanent IVC filter.Alternatively, the filters may be retrieved once the duration of PBprophylaxis has been achieved.

The invention provides in one particular case a retrievable and/orbio-resorbable filter.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more clearly understood from the followingdescription of some embodiments thereof, given by way of example only,with reference to the accompanying drawings, in which:

FIG. 1 is an isometric view of a vascular filter according to theinvention;

FIG. 2 is an end view of the filter of FIG. 1;

FIG. 3 is an isometric view of a support member of the filter of FIG. 1;

FIG. 4 is a developed, plan view of two capture members of the filter ofFIG. 1;

FIGS. 5 to 9 are partially cross-sectional, side views of the filter ofFIG. 1, in use;

FIGS. 10 to 12 are views similar to FIGS. 1 to 3 of another vascularfilter according to the invention;

FIG. 13 is an isometric view of another vascular filter according to theinvention;

FIG. 14 is an end view of the filter of FIG. 13 in a deliveryconfiguration;

FIG. 15 is an end view of the filter of FIG. 13 in a deployedconfiguration, in use;

FIGS. 16 and 17 are isometric views of support members of other vascularfilters according to the invention;

FIGS. 17( a) and 17(b) are side views of capture members of othervascular filters according to the invention;

FIG. 18 is an isometric view of capture members of another vascularfilter according to the invention;

FIG. 19 is an end view of the capture members of FIG. 18;

FIG. 20 is a plan view of one of the capture members of FIG. 18;

FIG. 21 is an end view of capture members of another vascular filteraccording to the invention;

FIGS. 22 and 23 are isometric views of further vascular filtersaccording to the invention;

FIGS. 24 to 26 are views similar to FIGS. 1 to 3 of another vascularfilter according to the invention;

FIG. 26( a) is an isometric view of another vascular filter according tothe invention;

FIG. 26( b) is a side view of the filter of FIG. 26( a);

FIG. 26( c) is an end view of the filter of FIG. 26( a);

FIG. 26( d) is a side view of the filter of FIG. 26( a) in a capturingconfiguration, in use;

FIG. 26( e) is an end view of the filter of FIG. 26( d) in the capturingconfiguration, in use;

FIGS. 26( f) and 26(g) are views similar to FIGS. 26( d) and 26(e) ofthe filter of FIG. 26( a) in an open configuration, in use;

FIG. 26( h) is a view similar to FIG. 26( d) of another vascular filteraccording to the invention;

FIGS. 26( i) and 26(j) are views similar to FIGS. 26( b) and 26(c) ofanother vascular filter according to the invention;

FIG. 26( k) is a side view of part of the filter of FIG. 26( i);

FIG. 26( l) is an end view of the part of FIG. 26( k);

FIG. 26( m) is an enlarged, end view of the part of FIG. 26( l);

FIGS. 26( n) and 26(o) are enlarged, end views of parts of the filter ofFIG. 26( i);

FIGS. 27 and 28 are views similar to FIGS. 1 and 2 of another vascularfilter according to the invention in a capturing configuration;

FIG. 29 is an isometric view of capture members and a support member ofthe filter of FIGS. 27 and 28 in an open configuration;

FIG. 30 is an isometric view of a holder member of the filter of FIGS.27 and 28;

FIG. 31 is an isometric view of a holder member of another vascularfilter according to the invention;

FIGS. 32 to 36 are partially cross-sectional, side views of the filterof FIGS. 27 and 28, in use;

FIGS. 37 to 39 are views similar to FIGS. 27 to 29 of another vascularfilter according to the invention;

FIG. 39( a) is an isometric view of another vascular filter according tothe invention in a collapsed delivery configuration;

FIG. 39( b) is an isometric view of the filter of FIG. 39( a) in anexpanded deployed configuration;

FIGS. 40 to 44 are partially cross-sectional, side views of the filterof FIGS. 39( a) and 39(b), in use;

FIGS. 44( a) and 44(b) are views similar to FIGS. 39( a) and 39(b) ofanother vascular filter according to the invention;

FIGS. 45 to 49 are partially cross-sectional, side views of the filterof FIGS. 27 and 28, in use;

FIGS. 50 and 51 are views similar to FIGS. 27 and 29 of a furthervascular filter according to the invention;

FIG. 52 is an isometric view of one of the capture members of the filterof FIGS. 50 and 51;

FIG. 52( a) is an isometric view of another vascular filter according tothe invention;

FIG. 52( b) is a side view of the filter of FIG. 52( a);

FIG. 52( c) is an end view of the filter of FIG. 52( a);

FIG. 52( d) is an enlarged, side view of part of the filter of FIG. 52(b);

FIG. 52( e) is an enlarged, end view of part of the filter of FIG. 52(c);

FIGS. 52( f) and 52(g) are end views of the filter of FIG. 52( e), inuse;

FIGS. 52( h) to 52(n) are partially cross-sectional, side views of thefilter of FIG. 52( a), in use;

FIG. 53 is an isometric view of another vascular filter according to theinvention;

FIG. 54 is a partially cross-sectional, side view of the filter of FIG.53, in use;

FIGS. 55 and 56 are isometric views of further vascular filtersaccording to the invention;

FIGS. 57 and 58 are partially cross-sectional, side views of the filterof FIG. 56, in use;

FIG. 59 is an isometric view of one of the support members of the filterof FIG. 56;

FIGS. 60 to 63 are views similar to FIGS. 56 to 59 of another vascularfilter according to the invention;

FIG. 63( a) is an isometric view of another vascular filter according tothe invention in a collapsed delivery configuration;

FIG. 63( b) is an isometric view of the filter of FIG. 63( a) in anexpanded deployed configuration;

FIG. 63( c) is a partially cut-away, isometric view of the filter ofFIG. 63( a), in use;

FIGS. 63( d) to 63(g) are views similar to FIGS. 56 to 59 of anothervascular filter according to the invention;

FIG. 64 is a partially cross-sectional, side view of another vascularfilter according to the invention, in use;

FIG. 65 is a side view of a part of the filter of FIG. 64;

FIG. 66 is a front view of the part of FIG. 65;

FIG. 67 is an isometric view of a further vascular filter according tothe invention;

FIG. 68 is an end view of the filter of FIG. 67 in a deployedconfiguration;

FIG. 69 is an end view of the filter of FIG. 67 in a deliveryconfiguration;

FIG. 70 is an isometric view of another vascular filter according to theinvention;

FIGS. 71 to 73 are views similar to FIGS. 67 to 69 of a further vascularfilter according to the invention;

FIGS. 74 to 76 are partially cross-sectional, side views of the filterof FIGS. 71 to 73, in use;

FIGS. 77 and 78 are views similar to FIGS. 1 and 2 of another vascularfilter according to the invention; and

FIG. 79 is an isometric view of a further vascular filter according tothe invention.

DETAILED DESCRIPTION

In this patent specification, the term “proximal” will be understood tomean the end closest to a user when carrying out a procedure accessedfrom a femoral vein, or the caudal end. Similarly the term “distal” willbe understood to mean the end furthest from a user when carrying out aprocedure accessed from a femoral vein, or the cranial end.

Referring to the drawings, and initially to FIGS. 1 to 9 thereof, thereis illustrated a vascular filter assembly according to the invention.The vascular filter assembly comprises a vascular filter 1 according tothe invention and a delivery catheter 9 for delivering the filter 1 to adesired location in a blood vessel, such as the inferior vena cava 4.The vascular filter 1 is suitable for use as an inferior vena cavafilter in the inferior vena cava 4 to capture thrombus 8 passing throughthe inferior vena cava 4 towards the heart and the lungs. The vascularfilter 1 may thus be used to prevent pulmonaryembolism.

The filter 1 comprises a support hoop 2 and four or more capture arms 3for capturing thrombus 8 passing through the inferior vena cava 4.

The support hoop 2 comprises a wire element 5 which extendscircumferentially in a sinusoid wave pattern (FIG. 3):

The support hoop 2 is movable between a collapsed delivery configuration(FIG. 5) and an expanded deployed configuration (FIG. 6). When thefilter 1 is deployed in the inferior vena cava 4, the support hoop 2extends circumferentially around the internal wall of the inferior venacava 4 (FIG. 6).

The support hoop 2 is biased radially outwardly towards the deployedconfiguration. When the filter 1 is deployed in the inferior vena cava4, the support hoop 2 exerts a force radially outwardly on the internalwall of the inferior vena cava 4. In this manner the support hoop 2supports the four capture arms 3 in position relative to the wall of theinferior vena cava 4.

Each capture arm 3 is attached to the support hoop 2 by wrapping orknotting or bonding an end of the capture arm 3 around the wire element5 (FIG. 1.). The four capture arms 3 extend in a substantially straightline to an apex 6, where the four capture arms 3 engage each other (FIG.1). In this manner the four capture arms 3 define a generally conicallyshaped capture region 7 within which thrombus 8 may be captured (FIG.7). When the filter 1 is deployed in the inferior vena cava 4, the apex6 is substantially in-line with the longitudinal axis B-B extendingthrough the centre of the inferior vena cava 4 (FIG. 6), and the captureregion 7 is located in the region of the centre of the inferior venacava 4 (FIG. 6). The capture arms 3 may be taut as shown or hang looselyin the bloodstream.

The capture arms 3 are movable between a collapsed deliveryconfiguration (FIG. 5) and an expanded deployed configuration (FIG. 6).When the filter 1 is deployed in the inferior vena cava 4, the capturearms 3 extend in the direction of blood flow A through the inferior venacava 4 (FIG. 6). The capture arms 3 are biased towards the deployedconfiguration.

Each of the capture arms 3 is of a biodegradable and/or bioabsorbablematerial. Similarly, the support hoop 2 may also be formed from abiodegradable and/or bio-absorbable material.

The filter element 1 has a taper configuration. The woven biodegradablearms 3 have a double taper (FIG. 4). The element 3 may equally be formedfrom a monofilament or multi-filament structure.

The filter 1 has an even number of elements 3 (FIG. 2). In analternative configuration the filter may have an odd number of elements3.

The multiple elements 3 degrade based on circumference from centre tooutside of the vessel 4.

By increasing the number of capture arms 3, the size between adjacentarms 3 is reduced to enhance filtering performance.

The delivery catheter 9 comprises a restraining sheath 10 which coversat least part of the collapsed filter 1 in a delivery configuration(FIG. 5). The sheath 10 is movable proximally relative to the filter 1to a deployed configuration to uncover the filter 1 and thus facilitatedeployment of the filter 1 (FIG. 6).

The filter element 3 with the tapered configuration may be formed in avariety of possible manners. For example by casting, dipping into apolymer solution with an extraction rate controlled to allow evaporationof solvent and deposition of polymer. The filter element 3 may bealternatively formed by extruded bump tubing, in which case thethermoplastic polymer is extruded into the tapered configuration.

In use the support hoop 2 and the four capture arms 3 are collapsed tothe delivery configuration, and at least partially loaded into thedelivery catheter 9. The delivery catheter 9 is advanced through theinferior vena cava 4 until the collapsed filter 1 reaches the desiredlocation in the inferior vena cava 4 (FIG. 5) The restraining sheath ofthe delivery catheter 9 is then moved proximally relative to the filter1 to fully uncover the filter 1. Due to the biasing nature of thesupport hoop 2 and the capture arms 3, the support hoop 2 and thecapture arms 3 move from the collapsed delivery configuration to theexpanded deployed configuration (FIG. 6). In the deployed configuration,the support hoop 2 exerts a radially outwardly force on the internalwall of the inferior vena cava 4 to support the capture arms 3 in thedesired position in the inferior vena cava 4.

In the event of thrombus 8 passing through the inferior vena cava 4towards the heart and the lungs, the thrombus 8 will be captured in thecapture region 7 of the filter 1 (FIG. 7). The thrombus 8 will thus beprevented from passing into the heart and the lungs which couldotherwise lead to pulmonaryembolism. The captured thrombus 8 willgradually be broken down by the body into smaller size particles 100,which will significantly reduce the risk of embolism (FIG. 8).

Due to the biodegradable/bioabsorbable material of the capture arms 3,the capture arms 3 will eventually biodegrade/bioabsorb (FIG. 9). Thusonly the support hoop 2 will remain in the inferior vena cava 4.

The delivery systems for delivery of the vena cava filter 1 may employpush and/or pull from either the jugular or femoral side.

The delivery system may use rotational deployment.

The delivery system may be a rapid exchange system for single operatordeployment.

The delivery system may use linear ratchet deployment and/or rotationalratchet deployment. The operator preferably keeps purchase on the filter1 until the location is finalised. The delivery system may be a pushforward system. In this case the operator aligns the distal cathetermarker to the location of mural attachment, and then pushes out thefilter 1.

It will be appreciated that part or all of the support hoop 2 may bebiodegradable/bioabsorbable, so that no part of the filter 1 will remainpermanently in the inferior vena cava 4.

In FIGS. 10 to 12 there is illustrated another vascular filter 20according to the invention, which is similar to the vascular filter 1 ofFIGS. 1 to 9, and similar elements in FIGS. 10 to 12 are assigned thesame reference numerals.

In this case the support hoop 21 is provided in the form of a mesh ortrellis 23. The mesh/trellis 23 comprises a number of openings 22therethrough.

The trellis filter 20 of FIGS. 10 to 12 is similar to a mural trelliswith a number of woven elements 3 extending to a proximal point 6. Theelements 3 may be joined, or may be not joined at the apex 6.

The filter 20 may be of metallic material and/or of biodegradablematerial. For example the filter 20 may be a combination of a metallicmural 21 and biodegradable elements 3.

The trellis design may be either self expanding or balloon expandable.

In one embodiment the trellis 23 comprises thin wires with weave fixedat ends to prevent unravelling. In another embodiment the trellis 23comprises thin wires interwoven with free ends. Either embodiment may beused for the mural element 21.

FIGS. 13 to 15 illustrate a further vascular filter 30 according to theinvention, which is similar to the vascular filter 20 of FIGS. 10 to 12,and similar elements in FIGS. 13 to 15 are assigned the same referencenumerals.

In this case the support hoop 31 comprises a body portion 32 and aplurality of openings 33 extending through the body portion 32.

In the collapsed delivery configuration the support hoop 31 has a spiralconfiguration (FIG. 14). In the expanded deployed configuration, one end34 of the support hoop 31 overlaps the other end 35 of the support hoop31.

The openings 33 in the support hoop 31 facilitate tissue ingrowth 36(FIG. 15).

The support hoop 31 may be a coil based system. FIG. 14 illustrates theclosed configuration, and FIG. 15 illustrates the open configuration.

The wall of the support hoop 31 may be planar or be of an open structure(FIG. 13).

The element structure 3 may be knotted using sutures to the support hoop31.

It will be appreciated that a variety of possible shapes andconfigurations are possible for the support hoop. For example, FIG. 16illustrates a support hoop 40 which comprises a wire element 41 whichextends circumferentially in a jagged wave pattern, FIG. 17 illustratesa support hoop 50 which comprises a body portion 51 which extendscircumferentially in a square wave pattern.

The support hoop may have a peak to peak design in the circular deployedconfiguration (FIG. 16). The support hoop may be formed of fixed lengthwires joined at each end to the wire on either side (FIG. 16), oralternatively may be cut from a single sheet (FIG. 17).

The support hoop designs of FIGS. 16 and 17 may also be suitable for useas a stent.

It will further be appreciated that the capture arms may engage eachother at the apex 6 in a variety of possible shapes and configurations.For example, the capture arms 3 may be fixedly attached to one anotherby a weld joint, solder or adhesive 55 at the apex 6 (FIG. 17( a)).Alternatively the capture arms 3 may be integrally formed from a singleelement 56 bent back on itself to form the capture arms 3 (FIG. 17( b)).As a further example in FIGS. 18 to 20 each capture arm 60 terminates ina curved, pointed tip 61 (FIG. 20). The tips 61 nest with one another atthe apex 6 (FIG. 19). In FIG. 21 each capture arm 70 terminates in astraight, pointed tip 71. The tips 71 nest with one another at the apex6 (FIG. 21).

FIG. 19 illustrates the nesting elements 60. The geometries of theelements 60 are configured to nest at the apex 6 of the filter such thata frame is erected during deployment that will not allow significantthrombus to pass.

Referring to FIG. 22 there is illustrated another vascular filter 80according to the invention, which is similar to the vascular filter 1 ofFIGS. 1 to 9, and similar elements in FIG. 22 are assigned the samereference numerals.

In this case the capture arms 3 extend in a curve to the apex 6. Theconcave portion of the curve faces radially outwardly.

In FIG. 23 there is illustrated a further vascular filter 90 accordingto the invention, which is similar to the vascular filter 80 of FIG. 22,and similar elements in FIG. 23 are assigned the same referencenumerals.

In this case the capture arms 3 extend in a curve to the apex 6. Theconvex portion of the curve faces radially outwardly. These capture arms3 may be moulded or machined into the configurations shown.

Possible geometries for the vena cava filter include conical shape,concave shape, and convex shape geometries.

FIGS. 24 to 26 illustrate another vascular filter 110 according to theinvention, which is similar to the vascular filter 1 of FIGS. 1 to 9,and similar elements in FIGS. 24 to 26 are assigned the same referencenumerals.

In this case the capture arm 112 is provided integral with the supporthoop 2. In particular the capture arm 112 is provided as an extension ofone of the sinusoid curves of the wire element 5 (FIG. 26). The otherthree capture arms 113 are similar to the capture arms 3 describedpreviously with reference to FIGS. 1 to 9.

The capture arms 112, 113 define an offset conically shaped captureregion 111. When the filter 110 is deployed in the inferior vena cava 4,the apex 6 is offset from the longitudinal axis B-B extending throughthe centre of the inferior vena cava 4, and the capture region 111 islocated in the region of the internal wall of the inferior vena cava 4.

The support hoop 2 may be a Nitinol (Ni Ti) sinusoid or may be astainless steel sinusoid. Alternatively the support hoop 2 may be of azigzag or crown design. The elements 113 may be of Nitinol stainlesssteel, titanium or a biodegradable material.

The filter 110 has a single extended element 112.

The offset filter 110 directs embolus to the side wall. This arrangementmay be advantageous. It may allow more blood flow at the centre of thevena cava 4 by directing thrombus 8 away from the centre of blood flow.

Alternatively, taper elements could be used.

Referring to FIGS. 26( a) to 26(g) there is illustrated another vascularfilter 300 according to the invention, which is similar to the vascularfilter 1 of FIGS. 1 to 9, and similar elements in FIGS. 26( a) to 26(g)are assigned the same reference numerals.

In this case the filter 300 comprises a proximal support hoop 302 at theproximal end of the filter 300, a distal support hoop 312 at the distalend of the filter 300, and a plurality of support struts 303 extendingbetween the proximal support hoop 302 and the distal support hoop 312.

The proximal support hoop 302 comprises a wire element 5 which extendscircumferentially around the wall of the inferior vena cava 4 in asinusoid wave pattern. Similarly the distal support hoop 312 comprises awire element 5 which extends circumferentially around the wall of theinferior vena cava 4 in a sinusoid wave pattern. The support struts 303extend longitudinally along the wall of the inferior vena cava 4. Thesupport struts 303 connect the proximal support hoop 302 to the distalsupport hoop 312. In this case the proximal support hoop 302, the distalsupport hoops 312 and the support struts 303 are formed integrally. Theproximal support hoop 302, the distal support hoop 312 and the supportstruts 303 may be of a shape-memory material, such as Nitinol.

As illustrated in FIG. 26( b), the distal end of the distal support hoop312 is located distally of the capture arms 3 and the apex 6, and theproximal end of the proximal support hoop 302 is located proximally ofthe capture arms 3.

The filter 300 also comprises a plurality of integral, or joined metal,or biodegradable/bioabsorbable barbs 301 to assist in anchoring thefilter 300 relative to the inferior vena cava 4.

In addition the filter 300 comprises two or more tensioning arms 304 andtwo or more connecting arms 305.

Each tensioning arm 304 is provided in the form of a cantilever arm. Thedistal end of the tensioning arm 304 is located distally of the apex 6,and the proximal end of the tensioning arm 304 is located proximally ofthe apex 6.

The tensioning arms 304 are movable between a capturing configuration(FIG. 26( d)) and an open configuration (FIG. 26( f)). In the capturingconfiguration, the tensioning arms 304 are inclined distally inwardlyrelative to the longitudinal axis of the inferior vena cava 4. In theopen configuration, the tensioning arms 304 are aligned parallel to thewall of the inferior vena cava 4. The tensioning arms 304 are biasedtowards the open configuration. The tensioning arms 304 may be of ashape-memory material, such as Nitinol.

The connecting arms 305 connect the tensioning arms 304 to the capturearms 3 at the apex 6. In this manner the tensioning arms 304 act totension the capture arms 3 to prevent the capture arms 3 from becomingslack and/or to prevent the apex 6 from moving off-centre. Alternativelythe tensioning arms 304 may originate at the caudal end of the filter300.

The connecting arms 305 are of a biodegradable/bioabsorbable material,in this case. In use, due to the biodegradable/bioabsorbable material ofthe connecting arms 305, the connecting arms 305 will eventuallybiodegrade/bioabsorb. This enables the tensioning arms 304 to move fromthe capturing configuration to the open configuration. Only the proximalsupport hoop 302, the distal support hoop 312, the support struts 303and the tensioning arms 304 remain in the inferior vena cava 4 (FIG. 26(f)).

FIGS. 26( a) to 26(g) illustrate the net filter design.

FIG. 26( b) illustrates the filtering elements 3, the tensioning element304, the tensioning filament 305, and the crown elements 302, 312.

The net filter design comprises the Nitinol frame 302, 303, 312 with atubular profile which has the number of bioabsorbable filaments 3attached and spanning across its diameter in order to create a filtercapable of trapping blood clots.

The Nitinol frame is a single component which comprises zigzag typedesign features called crowns 302, 312 at both its ends. This designallows the device 300 to be crimped or reduced in diameter so that itcan be delivered through the vascular system in a catheter of muchsmaller diameter than the vena cava 4.

The elastic energy in the deformed crowns 302, 312 enables the device300 to expand to the vessel diameter. The component is designed so thesecrowns 302, 312 exert outward radial pressure against the internal wallof the vena cava 4 within the range of vessels typically encountered.The two sets of crowns 302, 312 are linked by the connecting elements303.

The filter 300 is created by the number of bioabsorbable filaments 3which span the vessel lumen.

In order to deal with varying vessel diameters and to ensure that thefilaments 3 are capable of trapping and retaining a piece of blood clot,it is desirable that the absorbable elements 3 take up a tensionedconical configuration.

This is achieved by means of a tensioning feature 304 on the Nitinolframe and a tensioning filament 305 which pulls the filtering filaments3 in the cranial direction creating a tensioned filter net irrespectiveof the diameter of vessel 4 in which it is implanted.

The materials used have a known degradation profile such that they willprovide protection to the patient while they are at risk and once thisrisk is minimised the materials will breakdown and become metabolised.The tensioning feature 304 on the Nitinol frame will spring back to thevessel wall with sufficient outward pressure to promote endothelialcovering and encapsulation in tissue preventing or reducing the longterm complications of obstructing blood flow associated with permanentvena cava filters.

In order to ensure that no migration takes place, the small barbs 301are located at the cranial end of the connecting elements 303. They havesharp edges that are angled to anchor into the vessel tissue. The designfeatures barbs 301 which may face in either direction, or may haveseparate barbs 301 facing in opposite directions.

The filter 300 comprising bioabsorbable elements 3 creates a rigidconical shape across a wide range of vessel diameters. This may beachieved using the tensioning system shown in FIG. 26( b). The shortmetallic cantilever type elements 304 are connected to the tensioningfilament 305 that pulls the filtering element 3 in the cranial directionwhen positioned in the vessel 4 with a relatively smaller diameter.

These metallic elements 304 may be visualised during implantation usingfluoroscopy of other imaging technology and thus act as a radiopaqueindicator as to whether the filter elements 3 have degraded or not.

The metallic frame 304 bends inward to create the cone independent ofvessel size. This also creates a radiopaque indicator as to whether thefilter 300 is still functioning.

In FIG. 26( h) there is illustrated another vascular filter 320according to the invention, which is similar to the vascular filter 300of FIGS. 26( a) to 26(g), and similar elements in FIG. 26( h) areassigned the same reference numerals.

In this case the tensioning arms 304 are inclined proximally inwardlyrelative to the longitudinal axis of the inferior vena cava 4 in thecapturing configuration.

FIG. 26( h) illustrates the metallic tensioning element 304, the supportframe 312, the bioabsorbable filter elements 3, and the bioabsorbabletensioning element 305.

The filter 320 has the bioabsorbable elements 3 spanning across thevessel lumen protecting the patient while they are at risk of apulmonary embolism. These elements 3 break down when the risk haspassed. The elements 3 are connected to the metal frame which promotestissue ingrowth and becomes encapsulated in the vessel wall similar to astent.

The filter 320 has the ability to align the elements 3 in the centre ofthe vessel 4 so that they provide the maximum clot trapping ability. Awide range of blood vessel diameters may be encountered. Typically theinferior vena cava 4 may be in the range of 16 mm to 27 mm. The filter320 has the ability to relay visually whether the elements 3 haveabsorbed or not, i.e. whether the filter 320 is still functioning andthe patient protected from pulmonaryembolism.

The filter 320 has one or more tensioning elements 304 that remove anyslack in the filter elements 3 by increasing the filter cone angle asthe diameter increases. The small cantilever type metallic elements 304are deformed inward by the bioabsorbable element 305 to achieve thestretching out of the bioabsorbable filter elements 3 until they aretense and central in the vessel. The device 320 may be x-rayed toestablish if it is in the filter configuration or if it has converted byassessing the angle of the metallic tensioning elements 304.

FIGS. 26( i) to 26(m) illustrate another vascular filter 330 accordingto the invention, which is similar to the vascular filter 300 of FIGS.26( a) to 26(g), and similar elements in FIGS. 26( i) to 26(m) areassigned the same reference numerals.

In this case the filter 330 comprises a plurality of linking arms 331 tolink each capture arm 3 to the adjacent capture arm 3. The linking arms331 are of a biodegradable/bioabsorbable material.

The capture arms 3 comprise a plurality of openings 332 through the wallof the capture arms 3 at the apex 6. The openings 332 reduce the tensilestrength of the capture arms 3. In this manner the capture arms 3 areprovided with predetermined failure points to controlbiodegrading/bioabsorbing of the capture arms 3.

Similarly each linking arm 331 comprises an opening 333 through the wallof the linking arm 331. The opening 333 reduces the tensile strength ofthe linking arm 331. In this manner the linking arm 331 is provided witha predetermined failure point to control biodegrading/bioabsorbing ofthe linking arm 331.

FIG. 26( i) illustrates the tensioning arm 304, and the tensioningfilament 305.

The filter 330 has bioabsorbable elements 3 spanning across the vessellumen protecting the patient while they are at risk of a pulmonaryembolism. These elements 3 break down when the risk has passed. Theelements 3 are connected to the metal frame which will promote tissueingrowth and become encapsulated in the vessel wall similar to a stent.

Maintaining the conical shape in which any thromboemboli caught by thefilter 330 are stored in a central location may be an important feature,as this exposes the clot 8 to the highest flow rates. Consequently theclot 8 may be lysed in a shorter time period and the risk of IVCocclusion due to thrombosis may be reduced or minimised.

The absorbable net design 330 is manufactured in one component and mayoffer a more consistent concial filter shape and clot trappingefficiency than a series of single filaments 3. The net can adjust tovarying diameters by means of the tensioning system provided by thetensioning filament 305 and the tensioning arm 304.

The filter 330 may be made by producing a cone shaped film and cutting ashape in the film to produce a filter capable of protecting the patientfrom pulmonary embolism. This may be achieved by solution casting apolymer film and cutting away material to achieve various filter shapesthat preserve blood flow yet filter pieces of thrombi efficiently. Thecutting process would be achieved using laser technology to ensureaccurate dimensioning and freedom of filter design.

The component may be designed so that it will degrade initially in acontrolled location by designing areas of reduced cross sectional areainto the device. This will have the advantage of allowing the net toreduce to single strands and minimise the risk of a clinicallysignificant pulmonary emboli.

The component may be made from a compliant material such asPolycaprolactone and copolymers of caprolactone and Lactide and/orGylcolide. Other suitable polymers would be polymers derived fromPolyhydroxybutyrate.

Referring to FIGS. 27 to 30 and 32 to 36 there is illustrated a furthervascular filter 120 according to the invention, which is similar to thefilter 1 of FIGS. 1 to 9, and similar elements in FIGS. 27 to 30 and 32to 36 are assigned the same reference numerals.

In this case the filter 120 comprises six capture arms 121 integrallyformed with the support hoop 2. The capture arms 121 are movable betweena capturing configuration (FIG. 27) and an open configuration (FIG. 29).In the capturing configuration, the capture arms 121 extend to the apex6 and define the conically shaped capture region 7. The capture arms 121are biased towards the open configuration, and a holder tube 122 isprovided around the ends of the capture arms 121 to hold the capturearms 121 in the capturing configuration. The holder tube 122 isbiodegradable and/or bioabsorbable. Upon biodegrading/bioabsorbing ofthe holder tube 122, the capture arms 121 are free to move from thecapturing configuration to the open configuration (FIG. 29). The capturearms 121 are not biodegradable or bioabsorbable.

In use, in the deployed configuration, the support hoop 2 is partiallyembedded in the internal wall of the inferior vena cava 4 to support thecapture arms 121 in the desired position in the inferior vena cava 4(FIG. 33). Due to the biodegradable/bioabsorbable material of the holdertube 122, the holder tube 122 will eventually biodegrade/bioabsorb (FIG.36), which enables the capture arms 121 to move from the capturingconfiguration to the open configuration. The support hoop 2 and thecapture arms 121 remain in the inferior vena cava 4.

It will be appreciated that a variety of possible shapes andconfigurations are possible for the holder member which holds thecapture arms 121 in the capturing configuration. For example in FIG. 31,the holder member is provided in the form of a bioabsorbable and/orbiodegradable coil 130 around the ends of the capture arms 121 to holdthe capture arms 121 in the capturing configuration.

The shape memory of the capture arms 121 are configured to remember atubular shape. The only biodegradable element of the filter 120 is theholder 122 at the apex 6 of the filter 120.

The apex suture 130 bioresolves and the arms 121 revert to the tubularconfiguration (FIG. 31). Alternatively, the cap 122 at the apex 6 can bebio-resorbed (FIG. 30).

The filter arms 121 are not retrieved in this embodiment. Thebio-resorbable point 122 allows the filler (Ni Ti) 121 or other materialto relax to the wall and remain in the body.

Alternatively, the filter cap 122 may not be resorbable but may beretrieved by a snare or other removal device.

Another alternative is to replace the bio-resorbable cap by way of aninterventional procedure to extend the period for which protection isprovided to the patient.

In a further alternative, a metallic or bio-stable polymer element maybe used to replace the filter cap to convert the implant device into apermanent implant. Alternatively the permanent configuration may bewelded or otherwise permanently joined at the apex.

In FIGS. 37 to 39 there is illustrated another vascular filter 140according to the invention, which is similar to the vascular filter 120of FIGS. 27 to 30 and 32 to 36, and similar elements in FIGS. 37 to 39are assigned the same reference numerals.

In this case the support hoop 141 comprises a wire element 142 whichextends circumferentially in a plane.

As illustrated in FIG. 39 the free end 143 of each capture arm 121curves radially outwardly.

FIGS. 39( a) to 44 illustrate another vascular filter 145 according tothe invention, which is similar to the vascular filter 140 of FIGS. 37to 39, and similar elements in FIGS. 39( a) to 44 are assigned the samereference numerals.

In this case the support hoop 146 comprises a wire element 147 whichextends circumferentially in a sinusoid pattern in the collapseddelivery configuration (FIG. 39( a)), and which extendscircumferentially in a plane in the expanded deployed configuration(FIG. 39( b)).

As illustrated in FIGS. 40 to 44, the filter 145 may be delivered to thedesired location in the inferior vena cava 4 and deployed at the desiredlocation using the delivery catheter 9 in a manner similar to thatdescribed previously with reference to FIGS. 1 to 9.

Referring to FIGS. 44( a) and 44(b) there is illustrated anothervascular filter 148 according to the invention, which is similar to thevascular filter 140 of FIGS. 37 to 39, and similar elements in FIGS. 44(a) and 44(b) are assigned the same reference numerals.

In this case the support hoop 141 comprises the wire element 142 whichextends circumferentially in a plane. In the collapsed deliveryconfiguration the plane of the support hoop 141 is inclined relative toa plane perpendicular to the longitudinal axis of the inferior vena cava4 (FIG. 44( a)). In the expanded deployed configuration, the plane ofthe support hoop 141 may or may not be inclined relative to the planeperpendicular to the longitudinal axis of the inferior vena cava 4 (FIG.44( b)).

Alternatively, the filter 120, as described previously with reference toFIGS. 27 to 30, may be delivered to the desired location in the inferiorvena cava 4 and deployed at the desired location using another deliverycatheter 150 (FIGS. 45 to 49). The delivery catheter 150 comprises aballoon member 151 which is inflatable from a collapsed deliveryconfiguration (FIG. 45) to an expanded deployed configuration (FIG. 46),and deflatable from the expanded deployed configuration to the collapseddelivery configuration (FIG. 47).

In use the support hoop 2 and the six capture arms 121 are collapsed tothe delivery configuration, and mounted around the balloon member 151.The delivery catheter 150 is advanced through the inferior vena cava 4until the collapsed filter 120 reaches the desired location in theinferior vena cava 4 (FIG. 45). The balloon member 151 is then inflatedto move the support hoop 2 and the capture arms 121 from the collapseddelivery configuration to the expanded deployed configuration (FIG. 46).In the deployed configuration, the support hoop 2 exerts a radiallyoutward force on the internal wall of the interior vena cava 4 tosupport the capture arms 121 in the desired position in the inferiorvena cava 4.

The balloon member 151 is deflated from the expanded deployedconfiguration to the collapsed delivery configuration, and the deliverycatheter 150 is withdrawn (FIG. 47).

In the event of thrombus 8 passing through the inferior vena cava 4towards the heart and the lungs, the thrombus 8 will be captured in thecapture region 7 of the filter 120 (FIG. 48). The captured thrombus 8will gradually be broken down by the body into smaller size particles,which significantly reduce the risk of embolism.

Due to the biodegradable/bioabsorbable material of the holder tube 122,the holder tube 122 will eventually biodegrade/bioabsorb (FIG. 49),which enables the capture arms 121 to move from the capturingconfiguration to the open configuration. The support hoop 2 and thecapture arms 121 remain in the inferior vena cava 4.

FIGS. 45 to 49 illustrate the balloon expandable vena cava filter 120which has non shape memory metals or polymers. The filter 120 is mountedonto the balloon catheter 150.

The distal tip of the balloon may be inverted to minimise space used bythe balloon.

A tip marker may be incorporated to allow guidewire pull back fordeployment.

FIGS. 50 to 52 illustrate another vascular filter 160 according to theinvention, which is similar to the vascular filter 120 of FIGS. 27 to 30and 32 to 36 and similar elements in FIGS. 50 to 52 are assigned thesame reference numerals.

In this case, each capture arm 161 is formed separately from the supporthoop 2 and is attached to the support hoop 2 in a snap-fit arrangement.

FIG. 52 illustrates the moulded element 161 which is snap fitted to thesinusoidal wire 5.

Alternatively, the capture arms 161 may be of polymer and may be weldedto the degradable holder tube 122 at the apex 6. The capture arm parts161 are biased towards the open position.

In FIGS. 52( a) to 52(n) there is illustrated a further vascular filter340 according to the invention, which is similar to the vascular filter120 of FIGS. 27 to 30 and 32 to 36, and similar elements in FIGS. 52( a)to 52(n) are assigned the same reference numerals.

In this case the filter 340 comprises a proximal support hoop 302, adistal support hoop 312, a plurality of support struts 303, and aplurality of biodegradable/bioabsorbable barbs 301, similar to thosedescribed previously with reference to FIGS. 26( a) to 26(g).

An opening 341 is provided at the distal end of each of the capture arms121, and a suture 342 extends through the opening 341 to hold thecapture arms 121 in the capturing configuration.

The suture 342 is of a biodegradable/bioabsorbable material. The suture342 comprises an opening 343 through the wall of the suture 342. Theopening 343 reduces the tensile strength of the suture 342. In thismanner the suture 342 is provided with a predetermined failure point tocontrol biodegrading/bioabsorbing of the suture 342.

FIGS. 52( a) to 52(n) illustrate the apex filter design. FIG. 52( b)illustrates the filter element 121, the crown elements 302, 312, and theconnecting elements 303. While shown in a straight configuration, theelements 303 connecting the cranial and caudal ends may include curvedor angled elements. Such configurations may provide reduced lateralstiffness. Generally, the elements 303 will nest together for deliveryin the delivery system prior to deployment in the vena cava 4.

The apex design comprises the Nitinol frame 302, 312, 203, 121 and thesmall bioabsorbable element 342. The Nitinol frame is designed with thinelements that allow the device 340 to assume three separateconfigurations during its use:—

-   -   1. Delivery configuration.    -   2. Filter configuration    -   3. Open configuration

The component has a zigzag type support feature at both its ends 302,312 referred to in this specification as a crown, which allows thedevice 340 to be crimped or reduced in diameter so that it can bedelivered through the vascular system in a catheter of much smallerdiameter than the inferior vena cava 4.

The elastic energy in the deformed crowns 302, 312 enable the device 340to expand to the vessel diameter. The component is designed so thesecrowns 302, 312 exert outward radial pressure against the internal wallof the vena cava 4 within the range of vessels typically encountered.

The two sets of crowns 302, 312 are linked by connecting elements 303,and originating from the caudal ends of these connecting elements 303are thin filter elements 121 which have a V-shape. These filter elements121 can be mechanically deformed and retained in a central conical shapein order to create a filter configuration.

The component is designed so that the crown elements 302, 312 andconnecting elements 303 are relatively stiff versus the filter elements121, making the outer profile of the component substantially cylindricalwhen the filter elements 121 are deformed inward. This ensures that thecrown elements 302, 312 and connecting elements 303 remain in contactwith the wall while the device 340 is in the filter configurationpromoting tissue ingrowth and minimising the risk of complications withvena cava filters such as migration and perforation.

The filter elements 121 are held together by means of the filament 342made from a small volume of bioabsorbable material. The material has aknown degradation profile such that it has sufficient strength to retainthe metal filter elements 121 in the filtering configuration while thepatient is at risk of a large embolus passing through the vena cava 4.Once the treatment period has passed, the filament 342 will havedegraded sufficiently for the elastic force of the metal filter elements121 to break the filament 342 and expand outward.

The filament 342 is tied through small eyelet features 341 at the end ofthe filter elements 121 and a knot is formed around one filter 121 suchthat once the filament 342 breaks it stays attached to that filterelement 121.

Once the filter elements 121 become free the device 340 assumes its openconfiguration. The filter elements 121 spring back to the vessel walland exert sufficient pressure to promote endothelial covering andencapsulation in tissue, negating any long term complications associatedwith obstructing the blood flow in the vena cava 4.

In order to ensure that no migration takes place small barbs 301 arelocated at the cranial end of the connecting elements 303. They havesharp edges that are angled to anchor into the vessel tissue. The designfeatures barbs 301 which may face in either direction, or may haveseparate barbs 301 facing in opposite directions.

FIGS. 52( a) to 52(n) illustrate the concept for the convertible bloodvessel filter 340 where the device 340 has three configurations, thedelivery configuration, filter configuration and the open configuration.

The filter configuration is used to trap thrombus while a patient may beat risk of a thromboembolic event; once the risk has passed the device340 can then be converted to the open configuration which no longerdisrupts blood flow.

The filter configuration is achieved by mechanically deforming theelements 121 of the device 340 and securing these filter elements 121together at a point within the blood vessel. The filter elements 121 areheld by the bioabsorbable securement feature 342, which may be releasedto allow the elements 121 to revert back to the open configuration.

In the filter configuration, there is sufficient radial pressure andvessel contact to prevent the device 340 from migrating due to movementof surrounding organs and/or the forces of blood flow. However theradial pressure is not sufficiently high to cause perforation of theblood vessel 4.

In the open configuration all elements of the implanted device 340 exertradial pressure against the blood vessel wall promoting tissue ingrowth.

This is achieved by having the device 340 that has a substantiallycylindrical outer profile with sufficient mechanical stiffness tomaintain the cylindrical outer profile when the filter elements 121 oflow mechanical stiffness are deformed centrally. The substantiallycylindrical outer profile allows the device 340 to have significantvessel contact over a large area in both the open and filterconfigurations substantially reducing the risk of clinical issues suchas perforation, migration and tilting.

The device 340 is constructed of a superelastic metal or polymer. In oneembodiment the device is constructed of Nitinol.

In one embodiment the device 340 is one piece cut from a laser machinedtube, expanded and heat set. In another embodiment the device 340 is anassembly of more than one part from either the same material or fromdiffering superelastic materials.

Having a substantially cylindrical outer profile provides a significantadvantage in terms of deployment. As the device 340 exits the deliverysystem, the initial portion of the device 340 will contact the vesselwall prior to full device exiting of the delivery system. This allowsfor accurate placement of the device 340; as illustrated in FIG. 52( i).

In addition it also results in a self centering device 340 preventingtilting and allowing for the maximum clot trapping efficiency.

As the biodegradable members degrade, the degradation products move intothe bloodstream and in themselves, if they are large enough, could posea risk to the patient of pulmonaryembolism. It is thus beneficial tohave a device that utilises only a small volume of bio-resorbablepolymer. Ideally a short length of filament in the order of 1-10 cms ofdiameter 0.4 mm, more ideally less than 0.3 mm, even more ideally lessthan 0.2 mm may be used.

Another approach to managing the volume of degradation products beingreleased into the bloodstream at any time interval is taught herein bymeans of controlling the filter element dimensions and thus the time atwhich those products are released.

FIG. 52( e) illustrates the bioabsorbable element 342 which isconfigured to break at some point away from the knot. The element 342 isknotted around the frame 121. The element 342 remains connected to oneelement 121 of the frame after the filament 342 breaks.

The suture 342 may have a particularly small volume of bioabsorbablematerial. For example the suture 342 may have a diameter of less than0.4 mm, ideally less than 0.3 mm, more ideally less than 0.2 mm.

By minimising the amount of bioabsorbable material that embolises andenters the blood stream, this reduces the risk of clinicalcomplications. The filament material 342 is tied to the ends of thecapture elements 121 in such a way that when it breaks the filament 342remains tied to one of the capture elements 121 and becomes apposed tothe vessel wall. This results in the bioabsorbable material 342 becomingencapsulated in tissue and absorbing therein. This may be achieved byknotting the suture 342 around one of the arms 121 as shown in FIG. 52(e). The suture 342 will break at a point away from the knot and releasethe capture element arms 121 bringing the suture 342 with one of thearms 121.

Introducing a point 343 along the suture 342 that is more susceptible tobiodegradation is beneficial with this type of design. This may beachieved by having the region 343 that has a lower cross sectional areathan the remainder of the filament 342.

In one embodiment this area of reduced cross section is achieved bylasering a small hole 343 through the filament material 342. Ideally thediameter of the hole 343 would be less than Ø0.1 mm. More ideally thediameter of the hole 343 would be Ø0.05 mm.

FIG. 52( f) illustrates the small hole 343 machined in the filament 342to create the controlled break area.

The filter elements 342 may have multiple microscopic holes or notchesdrilled or formed therein to provide a locus for failure away from thejoins or knots. This may be beneficial in that the location of eventualfailure of the elements 342 is known. Varying the size of the holes willallow the time to failure for each element 342 to be controlledindividually. Larger holes will result in a shorter time to failure.This may be beneficial in allowing the timing of degradation productsbeing released into the bloodstream to be controlled. Alternatively,varying the diameter of the elements 342 to sequentially largerdiameters will allow similar control over the time to failure of thefilter elements 342.

The reduced cross section may alternatively be achieved by softening thematerial with heat and creating a ‘necked down’ region which has areduced cross sectional area.

The convertible filter 340 anchors securely at its deployment site andminimises risk of migration. The filter 340 incorporates the small sharpbarbs 301 facing either direction which add fixation points for thedevice 340 and combined with the radial force of the design, minimiseany risk of migration. The barbs 301 may be made of a bioabsorbablematerial which degrades and metabolises after the device 340 has beenencapsulated in tissue. This will prevent any long term effects due toerosion and/or perforation of the vena cava 4 caused by the barb 301.

Suitable bioabsorbable materials for a bioabsorbable barb 301 and/or forthe filter filament 342 include:

-   -   Poly (p-dioxanone);    -   Poly (L-Lactide-co-e-Caprolactone);    -   Ideally the mole percentage of L-lactide monomer would be in the        range of 60% to 80%. More ideally the mole percentage of        L-lactide monomer would be in the range of 65% to 75%.    -   Poly (glycolide-co-trimethylene carbonate);    -   Ideally the mole percentage of L-lactide monomer would be in the        range of 60% to 80%. More ideally the mole percentage of        L-lactide monomer would be in the range of 65% to 75%.    -   Poly (hydroxy butyrate);    -   Poly (L-lactide-co-glycolide);    -   Ideally the mole percentage of L-lactide monomer would be        greater than 70%.    -   More ideally the mole percentage of L-lactide monomer would be        greater than 80%.    -   More ideally the mole percentage of L-lactide monomer would be        greater than 90%.

The design of FIGS. 52( a) to 52(n) provides a stent-like shape to thevena cava filter 340 giving it a cylindrical outer profile. This designprevents issues such as tilting and perforation and allows for accuratedeployment within the vessel 4. The frame design allows the filterelements 121 to be deformed centrally without affecting the cylindricalouter profile and once the risk period for thromboemboli has passedallows the filter 121 to spring back to a position apposed to the vesselwall.

The bioabsorbable element 342 stays attached to the frame 121 afteropening. Controlling the break up of the bioabsorbable element 342 andminimising the amount of material that embolises may be achieved bytying the filament 342 around one filter element end. Therefore, oncethe element 342 breaks, it will remain attached to the frame 121 andbecome encapsulated in the vein wall along with the frame 121. Acontrolled break point 343 may be added to the absorbable element 342away from the knot by any of the means described herein.

Having barbs 301 that are bioabsorbable offers a significant advantagein that they are only required in the short-term and once the framebecomes encapsulated in the vein wall they will no longer be requiredthus preventing any potential long-term erosion effects of having thebarbs 301 on the frame.

FIG. 52( h) illustrates the vena cava 4 being accessed transluminallyusing the delivery catheter 9. FIG. 52( i) illustrates the vena cavafilter 340 being deployed by pulling back the delivery catheter sheath10. FIG. 52( j) illustrates the device 340 deployed filteringthromboemboli within the vena cava 4. FIG. 52( k) illustrates the device340 capturing a large clot 8 that may have caused a pulmonary embolism.FIG. 52( l) illustrates the filter 340 in situ after the blood's ownnatural lysing processes have broken down the clot 8 over time. FIG. 52(m) illustrates that once the threat of pulmonary embolism has passed,the bioabsorbable retainer 342 breaks down and allows the filter arms121 to become apposed to the wall. FIG. 52( n) illustrates that overtime the frame 340 becomes encapsulated in tissue.

Referring to FIGS. 53 and 54 there is illustrated another vascularfilter 170 according to the invention, which is similar to the vascularfilter 120 of FIGS. 27 to 30 and 32 to 36, and similar elements in FIGS.53 and 54 are assigned the same reference numerals.

In this case when the filter 170 is deployed in the inferior vena cava4, the capture arms 121 extend in the direction opposite to thedirection of blood flow A through die inferior vena cava 4 (FIG. 54). Asa result, the capture arms 121 define an annular shaped capture region171 located in the region of the internal wall of the inferior vena cava4.

FIG. 53 illustrates the Nitinol sinusoid 2 and the inverted elements121. This configuration acts to divert embolism 8 from the centre of theflow to be retained close to the side of the vessel 4. It creates a typeof receiver region 171 to receive the thrombus 8.

In FIG. 55 there is illustrated another vascular filter 180 according tothe invention, which is similar to the vascular filter 90 of FIG. 23,and similar elements in FIG. 55 are assigned the same referencenumerals.

In this case the filter 180 comprises six balance arms 181 extendingfrom the support hoop 2 in the opposite direction to the capture arms 3.Each balance arm 181 is attached to the support hoop 2 by wrapping anend of the balance arm 181 around the wire element 5.

Each balance arm 181 is of a biodegradable and/or bioabsorbablematerial.

Each balance arm 181 extends in a curve. The convex portion of the curvefaces radially outwardly.

In use, due to the biodegradable/bioabsorbable material of the balancearms 181, the balance arms 181 will eventually biodegrade/bioabsorb.Thus only the support hoop 2 will remain in the interior vena cava 4.

The filter 180 may be of varying porosity. More space may be provided inthe distal sections. The filter 180 has a ball shape. There are no sharpedges on a ball. This may allow enhanced radial force on the vena cavawall for enhanced anchoring.

FIGS. 56 to 59 illustrate another vascular filter 190 according to theinvention, which is similar to the vascular filter 120 of FIGS. 27 to 30and 32 to 36 and similar elements in FIGS. 56 to 59 are assigned thesame reference numerals.

In this case the filter 190 comprises a plurality of support anchors 191instead of the support hoop. A support anchor 191 is fixedly attached toa proximal end of each capture arm 121. Upon deployment of the filter190 in the inferior vena cava 4, the support anchors 191 are embeddedinto the internal wall of the inferior vena cava 4 (FIG. 57). In thismanner the support anchors 191 support the capture arms 121 in positionrelative to the wall of the inferior vena cava 4.

The biodegradable barbs 191 secure the filter device 190 at the time ofimplantation and are resorbed either fully or partially at the time ofretrieval.

It is believed that use of the barbs 191 on permanent filters couldreduce long term implantation problems.

It is believed that the use of bio-resorbable barbs on any implant couldreduce long term implantation problems. In particular a barb could beover-moulded or formed onto any metallic or polymeric structure andformed into the desired shape to anchor it to the vascular or anatomicalstructure. Alternatively the barbs could be moulded, machined, or formedfrom pre-forms such as extruded tiles or rods. The benefits include thefact that after a period of time the barb would be absorbed and theirritation removed from the implant site. Barbs could be attached to theend of or any intermediate point that could come in contact with a bloodvessel during implantation by means of endovascular or surgicaltreatment.

Referring to FIGS. 60 to 63 there is illustrated another vascular filterassembly according to the invention. The vascular filter assemblycomprises a vascular filter 200 according to the invention and aretrieval catheter 202 for retrieving the filter 200 from a location inthe inferior vena cava 4. The vascular filter 200 is similar to thevascular filter 190 of FIGS. 56 to 59, and similar elements in FIGS. 60to 63 are assigned the same reference numerals.

In this case the support anchors 201 are shaped to facilitate removalfrom the internal wall of the inferior vena cava 4, upon application ofa removal force C in a direction parallel to the longitudinal axis B-Bof the inferior vena cava 4 (FIG. 62).

The retrieval catheter 202 comprises a hook 203 for engaging the holdertube 122 of the filter 200, and a reception space 204. The hook 203 ismovable proximally relative to the reception space 204 to at leastpartially receive the filter 200 in the reception space 204.

In use, when it is desired to retrieve the deployed filter 200 from theinferior vena cava 4; the retrieval catheter 202 is introduced into theinferior vena cava 4. The retrieval catheter 202 is advanced through theinferior vena cava 4 with the hook 203 within the reception space 204.

When the distal end of the retrieval catheter 202 is adjacent to theholder tube 122, the hook 203 is advanced distally out of the receptionspace 204 (FIG. 61) to engage the holder tube 122 of the filter 200. Thehook 203 is then moved proximally which exerts a retrieval force C onthe filter 200 in a direction parallel to the longitudinal axis B-B ofthe inferior vena cava 4. Due to the shape of the support anchors 201,this retrieval force C causes the support anchors 201 to be removed fromthe internal wall of the inferior vena cava 4 (FIG. 62). The filter 200is therefore free to be moved proximally into the reception space 204 bymoving the hook 203 proximally. The retrieval catheter 202 and theretrieval filter 200 are then withdrawn from the inferior vena cava 4.

FIG. 60 illustrates the directional barbs 201 for retrievability. Theblood flow A acts to better embed the barbs 201 in the vessel wall. Theretrieval system 203 pushes the barbs 201 downwards and away from theartery wall 4. These Figs. are illustrated with four filtering arms 121for schematic purposes only. It is intended that the invention may useany number of arms 121, for example up to a maximum of twenty foroptimum entrapment of thrombo-embolism.

Referring to FIGS. 63( a) to 63(c) there is illustrated another vascularfilter assembly according to the invention. The vascular filter assemblycomprises a vascular filter 165 according to the invention and theretrieval catheter 202. The vascular filter 165 is similar to thevascular filter 120 of FIGS. 27 to 30 and 32 to 36, and similar elementsin FIGS. 63( a) to 63(c) are assigned the same reference numerals.

In this case the filter 165 comprises a plurality of support arms 167instead of the support hoop. In the expanded deployed configuration, thesupport arms 167 extend radially outwardly from a hinge point 168 (FIG.63( b)).

The holder tube 122 is not biodegradable/bioabsorbable in this case.

In use, the hook 203 is movable proximally relative to the retrievalcatheter 202 to cause the distal end of the retrieval catheter 202 toengage the capture arms 166. Further movement of the hook 203 proximallyrelative to the retrieval catheter 202 exerts a collapsing force on thecapture arms 166 (FIG. 63( c)) to move the filter 165 from the expandeddeployed configuration to the collapsed delivery configuration.

In FIG. 63( b) the ends 122, 168 are tethered. On retrieval, the cap 122is engaged in the retrieval catheter 202, and the filter 165 is pusheddown to elongate the filter 165 (FIG. 63( c)).

The elongation of the filter 165 pulls the capture arms 166 off theinternal wall of the inferior vena cava 4.

The elongation of the filter 165 is based on hinge points at the vesselcontact areas of the device. In another embodiment the retrieval may beaccomplished from the proximal end by engaging the retrieval hoop at theproximal inverted apex. This embodiment would allow the implanted deviceto be retrieved from the femoral puncture site, which may beadvantageous.

FIGS. 63( d) to 63(g) illustrate a further vascular filter 205 accordingto the invention, which is similar to the vascular filter 190 of FIGS.56 to 59, and similar elements in FIGS. 63( d) to 63(g) are assigned thesame reference numerals.

In this case the filter 205 is a removable filter. The support anchors206 are biodegradable to facilitate retrieval of the filter 205 into theretrieval catheter 202 (FIG. 63( f)).

By looping individual legs with a torque controlled retrieval system, itwill allow individual detachment of the barbs 201, as illustrated inFIGS. 64 to 66 by rotating the retrieval system such that it engages thefilter arms individually and sequentially.

In FIGS. 64 to 66 there is illustrated another vascular filter assemblyaccording to the invention. The vascular filter assembly comprises avascular filter 210 according to the invention and a retrieval catheter212. The vascular filter 210 is similar to the vascular filter 190 ofFIGS. 56 to 59, and the retrieval catheter 212 is similar to theretrieval catheter 202 of FIGS. 60 to 63, and similar elements in FIGS.64 to 66 are assigned the same reference numerals.

The retrieval system incorporates an actuation to aid the removal of thefilter arms 121/anchors from the cava 4. Retrieval pulls back thecentral hub 122 and the filter arms 121 until the actuator 211 abuts theshoulder. Then due to the geometry, the individual arms 121 areselectively deflected in a sequence off the cava wall and towards thecentre reducing the retrieval force required.

FIGS. 67 to 69 illustrate a further vascular filter 220 according to theinvention, which is similar to the vascular filter 1 of FIGS. 1 to 9,and similar elements in FIGS. 67 to 69 are assigned the same referencenumerals.

In this case the filter 220 comprises a wire element 221 which extendscircumferentially and longitudinally in a spiral towards the apex 6 todefine the conically shaped capture region 7.

The larger diameter turns of the spiral at the proximal end 222 of thefilter 220 act as the support hoop to support the filter 220 in positionrelative to the internal wall of the inferior vena cava 4.

The small diameter turns of the spiral at the distal end 223 of thefilter 220 act as the capture arm to capture thrombus 8 passing throughthe inferior vena cava 4.

As illustrated in FIGS. 68 and 69, the spiral configuration enables thefilter 220 to be collapsed down in an efficient manner for delivery tothe desired location in the inferior vena cava 4.

In this case the wire element 221 is not of a biodegradable orbioabsorbable material.

Referring to FIG. 70 there is illustrated another vascular filter 230according to the invention, which is similar to the vascular filter 220of FIGS. 67 to 69, and similar elements in FIG. 70 are assigned the samereference numerals.

In this case, when the filter 230 is deployed in the inferior vena cava4, the wire element 221 extends towards the apex 6 in the directionopposite to the direction of blood flow A through the inferior vena cava4. As a result the wire element 221 defines an annular shaped captureregion 231 located in the region of the internal wall of the inferiorvena cava 4.

The large diameter turns of the spiral at the distal end 231 of thefilter 230 act as the support hoop.

FIGS. 67 to 70 illustrate coil vena cava filters 220, 230. The filter220 has a conical section 223 and a mural section 222. The mural section222 anchors the filter device 220 either with radial force or with barbswhich may be bio-resorbable. The coil pitch decreases towards the apex6. The coil may be concentric or non centric. The inverted coil designof FIG. 70 has its minimum pitch at the inversion.

The filter net 221 may absorb from inside to outside. The wall of thewire element 221 may be thicker at the outer section. The biodegradablefilter 229 may absorb from the inner section out.

In FIGS. 71 to 76 there is illustrated another vascular filter assemblyaccording to the invention. The vascular filter assembly comprises avascular filter 240 according to the invention and a catheter 241. Thevascular filter 240 is similar to the vascular filter 220 of FIGS. 67 to69, and the catheter 241 is similar to the retrieval catheter 202 ofFIGS. 60 to 63, and similar elements in FIGS. 71 to 76 are assigned thesame reference numerals.

In this case wire element 221 defines an offset conically shaped captureregion 242. When the filter 240 is deployed in the inferior vena cava 4,the apex 6 is offset from the longitudinal axis B-B extending throughthe centre of the inferior vena cava 4, and the capture region 242 islocated in the region of the internal wall of the inferior vena cava 4.

The catheter 241 is employed as a delivery catheter to deliver thefilter 240 to the desired location in the inferior vena cava 4 (FIGS. 74and 75), and as a retrieval catheter to retrieve the filter 240 from theinferior vena cava 4 (FIG. 76). The hook 203 of the catheter 241 isengagable with a corresponding notch 243 defined on the wire element221. The hook 203 is rotated to collapse the filter 240 from theexpanded deployed configuration (FIG. 72) to the collapseddelivery/retrieval configuration (FIG. 73), prior to moving the filter240 proximally into the reception space 204, as illustrated in FIG. 76.

Retrieval of the filter 240 may be performed by pulling the filterdevice 240 into the catheter 241. This retrieval may be simplified byrotating the coil filter 240 in the direction of the helix, which tendsto locally peel the coil 240 away from the intima. FIG. 76 illustratesthe vessel wall with the coil 240 being rotated away.

FIGS. 77 and 78 illustrate a further vascular filter 250 according tothe invention, which is similar to the vascular filter 1 of FIGS. 1 to9, and similar elements in FIGS. 77 and 78 are assigned the samereference numerals.

In this case the capture arms 251 extend in a cylindrical manner todefine a cylindrically shaped capture region 252.

Referring to FIG. 79 there is illustrated a further vascular filter 260according to the invention, which is similar to the vascular filter 250of FIGS. 77 and 78, and similar elements in FIG. 79 are assigned thesame reference numerals.

In this case the support hoop 261 is provided in the form of a mesh ortrellis 262. The mesh/trellis 262 comprises a number of openings 263therethrough.

The mesh design of FIG. 79 may employ a homogenous mesh, or a variablemesh, for example with larger openings closer to the wire 261. The meshmay be fabricated from a bio-resorbable material or may be metallic or abio-stable polymer.

The wire 261 may have a spiral/helical shape memory. The wire 261 mayoverlap on the walls or be joined at the extremities of the trellis 262.

The filter 260 has a wind sock type design. The mesh 251 is bonded tothe mural structure 261. The support hoop 261 may have a sinusoid form,or a spiral form, or a coil form.

The embolus diverting vena cava filter may be concentric with theembolus, or may be non concentric.

The invention is not limited to the embodiments hereinbefore described,with reference to the accompanying drawings, which may be varied inconstruction and detail.

The invention claimed is:
 1. A vascular filter comprising: capturemembers for capturing thrombus passing through a blood vessel; a tubularsupport frame for supporting the capture members relative to a wall of ablood vessel, the support frame including: a proximal hoop extendingcircumferentially; a distal hoop extending circumferentially; connectormembers extending between the proximal and distal hoop; wherein thefilter includes a holder member to hold the capture members in afiltering configuration, and the capture members are distributed in atubular fashion between the connector members in the absence of a holdermember such that the capture members and the connector members arenon-overlapping.
 2. A vascular filter as claimed in claim 1, wherein theholder member comprises a suture.
 3. A vascular filter as claimed inclaim 1, wherein the holder member comprises one or more predeterminedfailure regions.
 4. A vascular filter as claimed in claim 1, wherein theholder member is attached to one of the capture members such that oncethe holder member breaks it stays attached to said capture members.
 5. Avascular filter as claimed in claim 1, further including openings in thecapture members in the form of eyelets.
 6. A vascular filter as claimedin claim 1, wherein the proximal hoop extends circumferentially in acrown or sinusoid pattern.
 7. A vascular filter as claimed in claim 1,wherein the distal hoop extends circumferentially in a crown or sinusoidpattern.
 8. A vascular filter as claimed in claim 1, wherein the filtercomprises anchor barb elements on at least one support portionconfigured to be embedded at least partially into a wall of a bloodvessel.
 9. A vascular filter as claimed in claim 1, wherein the capturemembers are biased towards an open configuration, at which all membersof the vascular filter exert pressure against a vessel to promote tissueencapsulation.
 10. A vascular filter as claimed in claim 1, wherein thecapture members extend towards an apex when in the capturingconfiguration.
 11. A vascular filter as claimed in claim 1, wherein thefilter comprises tensioning members to tension the capture members. 12.A vascular filter as claimed in claim 1, wherein the filter is a venacava filter.
 13. A vascular filter comprising: capture members forcapturing thrombus passing through a blood vessel; a tubular supportframe for supporting the capture members relative to a wall of a bloodvessel, the support frame including: a proximal hoop extendingcircumferentially in a crown or sinusoid pattern; a distal hoopextending circumferentially in a crown or sinusoid pattern; connectormembers extending between the proximal and distal hoop; wherein thefilter includes a holder member to hold the capture members in afiltering configuration, and the capture members are distributed in atubular fashion between the connector members in the absence of a holdermember such that the capture members and the connector members arenon-overlapping.
 14. A vascular filter as claimed in claim 13, whereinthe capture members are biased towards an open configuration, at whichall members of the vascular filter exert pressure against a vessel topromote tissue encapsulation.
 15. A vascular filter comprising: capturemembers for capturing thrombus passing through a blood vessel; a tubularsupport frame for supporting the capture members relative to a wall of ablood vessel, the support frame including: a proximal hoop extendingcircumferentially; a distal hoop extending circumferentially; connectormembers extending between the proximal and distal hoop; wherein thefilter includes a holder member to hold the capture members in afiltering configuration with an apex located between the proximal hoopand the distal hoop, and the capture members are distributed in atubular fashion between the connector members in the absence of a holdermember such that the capture members and the connector members arenon-overlapping.
 16. A vascular filter as claimed in claim 15, whereinthe capture members are biased towards an open configuration, at whichall members of the vascular filter exert pressure against a vessel topromote tissue encapsulation.